Bell in U.S. Pat. No. 4,216,501 discloses an optical record blank comprising a light-reflective layer, a light-transmissive layer overlying the reflective layer and a light-absorptive layer overlying the transmissive layer. The thickness of the layers are chosen in relation to the layers' optical constants such that a low-reflection and preferably an anti-reflection condition occurs at the surface of the absorptive layer. A recording light beam incident on the trilayer structure causes an ablation or deformation of the absorptive layer resulting in a variation of reflectivity in the information record.
Some materials, such as selenium, have desirable properties as an absorptive layer to obtain a high recording sensitivity and a high signal-to-noise ratio for optimum playback performance. Previously, these materials have been unusable at longer recording wavelengths because they become non-absorbing at these wavelengths.